Why does killing Warwick while his attack trigger is on the chain prevent it from doing anything, but Kog'Maw's deathknell still works after he dies?

Ruling: Warwick's trigger uses "here" which is a restriction that must be met both when the ability is placed on the chain and when it resolves. If Warwick is removed from the battlefield (moved to trash/hand), there is no longer a "here" location to reference, so the ability resolves but does nothing. Kog'Maw's deathknell uses "my battlefield" instead of "here", which functions differently, though the developers have admitted this isn't well-covered in the current comprehensive rules and will be clarified in version 1.2.

Sequence:

• When Warwick attacks, his trigger goes on the chain
• If Warwick is killed/removed before the trigger resolves, he is no longer at any location on the battlefield
• When the trigger resolves, it looks for "here" but Warwick has no "here" anymore
• The ability resolves but does nothing because the restriction cannot be met
• Kog'Maw's deathknell works because "my battlefield" is treated differently by developer ruling

Nuances:

• "Here" acts like a pointer that constantly references the unit's current location
• If Warwick moves to a different battlefield before his trigger resolves, the trigger will affect the new "here" location
• Abilities without locational restrictions (like Traveling Merchant's loot trigger) still resolve fully even if the unit is removed
• Kog'Maw's damage occurs after combat healing but before scoring
• The "my battlefield" wording needs additional rules support that doesn't currently exist in the comprehensive rules